Articles | Volume 22, issue 24
https://doi.org/10.5194/acp-22-15703-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-22-15703-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
15 Dec 2022
Research article |
| 15 Dec 2022
| 15 Dec 2022
Aerosol optical depth regime over megacities of the world
Kyriakoula Papachristopoulou
CORRESPONDING AUTHOR
Laboratory of Climatology and Atmospheric Environment, Sector of
Geography and Climatology, Department of Geology and Environment, National
and Kapodistrian University of Athens, Athens 15784, Greece
Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing,
National Observatory of Athens (IAASARS/NOA), Athens 15236, Greece
Department of Physics, ETH Zurich, Zurich 8093, Switzerland
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC), Davos 7260, Switzerland
Ioannis-Panagiotis Raptis
Laboratory of Climatology and Atmospheric Environment, Sector of
Geography and Climatology, Department of Geology and Environment, National
and Kapodistrian University of Athens, Athens 15784, Greece
Antonis Gkikas
Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing,
National Observatory of Athens (IAASARS/NOA), Athens 15236, Greece
Ilias Fountoulakis
Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing,
National Observatory of Athens (IAASARS/NOA), Athens 15236, Greece
Akriti Masoom
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC), Davos 7260, Switzerland
Stelios Kazadzis
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC), Davos 7260, Switzerland
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Ilias Fountoulakis, Kyriaki Papachristopoulou, Stelios Kazadzis, Gregor Hülsen, Julian Gröbner, Ioannis-Panagiotis Raptis, Dimitra Kouklaki, Akriti Masoom, Charalampos Kontoes, and Christos S. Zerefos
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Angelos Karanikolas, Natalia Kouremeti, Monica Campanelli, Victor Estellés, Masahiro Momoi, Gaurav Kumar, Stephan Nyeki, and Stelios Kazadzis
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Akriti Masoom, Stelios Kazadzis, Masimo Valeri, Ioannis-Panagiotis Raptis, Gabrielle Brizzi, Kyriakoula Papachristopoulou, Francesca Barnaba, Stefano Casadio, Axel Kreuter, and Fabrizio Niro
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Ilias Fountoulakis, Alexandra Tsekeri, Stelios Kazadzis, Vassilis Amiridis, Angelos Nersesian, Maria Tsichla, Emmanouil Proestakis, Antonis Gkikas, Kyriakoula Papachristopoulou, Vasileios Barlakas, Claudia Emde, and Bernhard Mayer
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Atmos. Meas. Tech., 17, 1851–1877, https://doi.org/10.5194/amt-17-1851-2024, https://doi.org/10.5194/amt-17-1851-2024, 2024
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Ruth A. R. Digby, Nathan P. Gillett, Adam H. Monahan, Knut von Salzen, Antonis Gkikas, Qianqian Song, and Zhibo Zhang
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The COVID-19 lockdowns reduced aerosol emissions. We ask whether these reductions affected regional aerosol optical depth (AOD) and compare the observed changes to predictions from Earth system models. Only India has an observed AOD reduction outside of typical variability. Models overestimate the response in some regions, but when key biases have been addressed, the agreement is improved. Our results suggest that current models can realistically predict the effects of future emission changes.
Antonio Fernando Almansa, África Barreto, Natalia Kouremeti, Ramiro González, Akriti Masoom, Carlos Toledano, Julian Gröbner, Rosa Delia García, Yenny González, Stelios Kazadzis, Stéphane Victori, Óscar Álvarez, Fabrice Maupin, Virgilio Carreño, Victoria Eugenia Cachorro, and Emilio Cuevas
Atmos. Meas. Tech., 17, 659–675, https://doi.org/10.5194/amt-17-659-2024, https://doi.org/10.5194/amt-17-659-2024, 2024
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This paper applies sun photometer synergies to improve calibration transference between different sun photometers and also enhance their quality assurance and quality control. We have validated this technique using different instrumentation, the WMO-GAW and NASA-AERONET references, under different aerosol regimes using the standard Langley calibration method as a reference.
Óscar Alvárez, África Barreto, Omaira E. García, Frank Hase, Rosa D. García, Julian Gröbner, Sergio F. León-Luis, Eliezer Sepúlveda, Virgilio Carreño, Antonio Alcántara, Ramón Ramos, A. Fernando Almansa, Stelios Kazadzis, Noémie Taquet, Carlos Toledano, and Emilio Cuevas
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In this work, we have extended the capabilities of a portable Fourier transform infrared (FTIR) instrument, which was originally designed to provide high-quality greenhouse gas monitoring within COCCON (COllaborative Carbon Column Observing Network). The extension allows the spectrometer to now also provide coincidentally column-integrated aerosol information. This addition of a reference instrument to a global network will be utilised to enhance our understanding of atmospheric chemistry.
Julian Gröbner, Natalia Kouremeti, Gregor Hülsen, Ralf Zuber, Mario Ribnitzky, Saulius Nevas, Peter Sperfeld, Kerstin Schwind, Philipp Schneider, Stelios Kazadzis, África Barreto, Tom Gardiner, Kavitha Mottungan, David Medland, and Marc Coleman
Atmos. Meas. Tech., 16, 4667–4680, https://doi.org/10.5194/amt-16-4667-2023, https://doi.org/10.5194/amt-16-4667-2023, 2023
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Spectral solar irradiance measurements traceable to the International System of Units (SI) allow for intercomparability between instruments and for their validation according to metrological standards. Here we also validate and reduce the uncertainties of the top-of-atmosphere TSIS-1 Hybrid Solar Reference Spectrum (HSRS). The management of large networks, e.g. AERONET or GAW-PFR, will benefit from reducing logistical overhead, improving their resilience and achieving metrological traceability.
Vasiliki Daskalopoulou, Panagiotis I. Raptis, Alexandra Tsekeri, Vassilis Amiridis, Stelios Kazadzis, Zbigniew Ulanowski, Vassilis Charmandaris, Konstantinos Tassis, and William Martin
Atmos. Meas. Tech., 16, 4529–4550, https://doi.org/10.5194/amt-16-4529-2023, https://doi.org/10.5194/amt-16-4529-2023, 2023
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Atmospheric dust particles may present a preferential alignment due to their shape on long range transport. Since dust is abundant and plays a key role to global climate, the elusive observation of orientation will be a game changer to existing measurement techniques and the representation of particles in climate models. We utilize a specifically designed instrument, SolPol, and target the Sun from the ground for large polarization values under dusty conditions, a clear sign of orientation.
Akriti Masoom, Ilias Fountoulakis, Stelios Kazadzis, Ioannis-Panagiotis Raptis, Anna Kampouri, Basil E. Psiloglou, Dimitra Kouklaki, Kyriakoula Papachristopoulou, Eleni Marinou, Stavros Solomos, Anna Gialitaki, Dimitra Founda, Vasileios Salamalikis, Dimitris Kaskaoutis, Natalia Kouremeti, Nikolaos Mihalopoulos, Vassilis Amiridis, Andreas Kazantzidis, Alexandros Papayannis, Christos S. Zerefos, and Kostas Eleftheratos
Atmos. Chem. Phys., 23, 8487–8514, https://doi.org/10.5194/acp-23-8487-2023, https://doi.org/10.5194/acp-23-8487-2023, 2023
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We analyse the spatial and temporal aerosol spectral optical properties during the extreme wildfires of August 2021 in Greece and assess their effects on air quality and solar radiation quantities related to health, agriculture, and energy. Different aerosol conditions are identified (pure smoke, pure dust, dust–smoke together); the largest impact on solar radiation quantities is found for cases with mixed dust–smoke aerosols. Such situations are expected to occur more frequently in the future.
Theano Drosoglou, Ioannis-Panagiotis Raptis, Massimo Valeri, Stefano Casadio, Francesca Barnaba, Marcos Herreras-Giralda, Anton Lopatin, Oleg Dubovik, Gabriele Brizzi, Fabrizio Niro, Monica Campanelli, and Stelios Kazadzis
Atmos. Meas. Tech., 16, 2989–3014, https://doi.org/10.5194/amt-16-2989-2023, https://doi.org/10.5194/amt-16-2989-2023, 2023
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Aerosol optical properties derived from sun photometers depend on the optical depth of trace gases absorbing solar radiation at specific spectral ranges. Various networks use satellite-based climatologies to account for this or neglect their effect. In this work, we evaluate the effect of NO2 absorption in aerosol retrievals from AERONET and SKYNET over two stations in Rome, Italy, with relatively high NO2 spatiotemporal variations, using NO2 data from the Pandora network and the TROPOMI sensor.
Michail Mytilinaios, Sara Basart, Sergio Ciamprone, Juan Cuesta, Claudio Dema, Enza Di Tomaso, Paola Formenti, Antonis Gkikas, Oriol Jorba, Ralph Kahn, Carlos Pérez García-Pando, Serena Trippetta, and Lucia Mona
Atmos. Chem. Phys., 23, 5487–5516, https://doi.org/10.5194/acp-23-5487-2023, https://doi.org/10.5194/acp-23-5487-2023, 2023
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Multiscale Online Non-hydrostatic AtmospheRe CHemistry model (MONARCH) dust reanalysis provides a high-resolution 3D reconstruction of past dust conditions, allowing better quantification of climate and socioeconomic dust impacts. We assess the performance of the reanalysis needed to reproduce dust optical depth using dust-related products retrieved from satellite and ground-based observations and show that it reproduces the spatial distribution and seasonal variability of atmospheric dust well.
Pantelis Kiriakidis, Antonis Gkikas, Georgios Papangelis, Theodoros Christoudias, Jonilda Kushta, Emmanouil Proestakis, Anna Kampouri, Eleni Marinou, Eleni Drakaki, Angela Benedetti, Michael Rennie, Christian Retscher, Anne Grete Straume, Alexandru Dandocsi, Jean Sciare, and Vasilis Amiridis
Atmos. Chem. Phys., 23, 4391–4417, https://doi.org/10.5194/acp-23-4391-2023, https://doi.org/10.5194/acp-23-4391-2023, 2023
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With the launch of the Aeolus satellite, higher-accuracy wind products became available. This research was carried out to validate the assimilated wind products by testing their effect on the WRF-Chem model predictive ability of dust processes. This was carried out for the eastern Mediterranean and Middle East region for two 2-month periods in autumn and spring 2020. The use of the assimilated products improved the dust forecasts of the autumn season (both quantitatively and qualitatively).
Antonis Gkikas, Anna Gialitaki, Ioannis Binietoglou, Eleni Marinou, Maria Tsichla, Nikolaos Siomos, Peristera Paschou, Anna Kampouri, Kalliopi Artemis Voudouri, Emmanouil Proestakis, Maria Mylonaki, Christina-Anna Papanikolaou, Konstantinos Michailidis, Holger Baars, Anne Grete Straume, Dimitris Balis, Alexandros Papayannis, Tomasso Parrinello, and Vassilis Amiridis
Atmos. Meas. Tech., 16, 1017–1042, https://doi.org/10.5194/amt-16-1017-2023, https://doi.org/10.5194/amt-16-1017-2023, 2023
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We perform an assessment analysis of the Aeolus Standard Correct Algorithm (SCA) backscatter coefficient retrievals against reference observations acquired at three Greek lidar stations (Athens, Thessaloniki and Antikythera) of the PANACEA network. Overall, 43 cases are analysed, whereas specific aerosol scenarios in the vicinity of Antikythera island (SW Greece) are emphasised. All key Cal/Val aspects and recommendations, and the ongoing related activities, are thoroughly discussed.
Huilin Huang, Yun Qian, Ye Liu, Cenlin He, Jianyu Zheng, Zhibo Zhang, and Antonis Gkikas
Atmos. Chem. Phys., 22, 15469–15488, https://doi.org/10.5194/acp-22-15469-2022, https://doi.org/10.5194/acp-22-15469-2022, 2022
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Using a clustering method developed in the field of artificial neural networks, we identify four typical dust transport patterns across the Sierra Nevada, associated with the mesoscale and regional-scale wind circulations. Our results highlight the connection between dust transport and dominant weather patterns, which can be used to understand dust transport in a changing climate.
Angelos Karanikolas, Natalia Kouremeti, Julian Gröbner, Luca Egli, and Stelios Kazadzis
Atmos. Meas. Tech., 15, 5667–5680, https://doi.org/10.5194/amt-15-5667-2022, https://doi.org/10.5194/amt-15-5667-2022, 2022
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The aim of this work is to investigate the limitations of calculating long-term trends of a parameter that quantifies the overall effect of atmospheric aerosols on the solar radiation. A main finding is that even instruments with good agreement between their observations can show significantly different linear trends. By calculating time-varying trends, the trend agreement is shown to improve. We also show that different methods of trend estimation can result in significant trend differences.
Kostas Eleftheratos, John Kapsomenakis, Ilias Fountoulakis, Christos S. Zerefos, Patrick Jöckel, Martin Dameris, Alkiviadis F. Bais, Germar Bernhard, Dimitra Kouklaki, Kleareti Tourpali, Scott Stierle, J. Ben Liley, Colette Brogniez, Frédérique Auriol, Henri Diémoz, Stana Simic, Irina Petropavlovskikh, Kaisa Lakkala, and Kostas Douvis
Atmos. Chem. Phys., 22, 12827–12855, https://doi.org/10.5194/acp-22-12827-2022, https://doi.org/10.5194/acp-22-12827-2022, 2022
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We present the future evolution of DNA-active ultraviolet (UV) radiation in view of increasing greenhouse gases (GHGs) and decreasing ozone depleting substances (ODSs). It is shown that DNA-active UV radiation might increase after 2050 between 50° N–50° S due to GHG-induced reductions in clouds and ozone, something that is likely not to happen at high latitudes, where DNA-active UV radiation will continue its downward trend mainly due to stratospheric ozone recovery from the reduction in ODSs.
Eleni Drakaki, Vassilis Amiridis, Alexandra Tsekeri, Antonis Gkikas, Emmanouil Proestakis, Sotirios Mallios, Stavros Solomos, Christos Spyrou, Eleni Marinou, Claire L. Ryder, Demetri Bouris, and Petros Katsafados
Atmos. Chem. Phys., 22, 12727–12748, https://doi.org/10.5194/acp-22-12727-2022, https://doi.org/10.5194/acp-22-12727-2022, 2022
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State-of-the-art atmospheric dust models have limitations in accounting for a realistic dust size distribution (emission, transport). We modify the parameterization of the mineral dust cycle by including particles with diameter >20 μm, as indicated by observations over deserts. Moreover, we investigate the effects of reduced settling velocities of dust particles. Model results are evaluated using airborne and spaceborne dust measurements above Cabo Verde.
Antonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Eleni Marinou, Nikos Hatzianastassiou, Jasper F. Kok, and Carlos Pérez García-Pando
Atmos. Chem. Phys., 22, 3553–3578, https://doi.org/10.5194/acp-22-3553-2022, https://doi.org/10.5194/acp-22-3553-2022, 2022
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We present a comprehensive climatological analysis of dust optical depth (DOD) relying on the MIDAS dataset. MIDAS provides columnar mid-visible (550 nm) DOD at fine spatial resolution (0.1° × 0.1°) over a 15-year period (2003–2017). In the current study, the analysis is performed at various spatial (from regional to global) and temporal (from months to years) scales. More specifically, focus is given to specific regions hosting the major dust sources as well as downwind areas of the planet.
Dimitris Karagkiozidis, Martina Michaela Friedrich, Steffen Beirle, Alkiviadis Bais, François Hendrick, Kalliopi Artemis Voudouri, Ilias Fountoulakis, Angelos Karanikolas, Paraskevi Tzoumaka, Michel Van Roozendael, Dimitris Balis, and Thomas Wagner
Atmos. Meas. Tech., 15, 1269–1301, https://doi.org/10.5194/amt-15-1269-2022, https://doi.org/10.5194/amt-15-1269-2022, 2022
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In this study we focus on the retrieval of aerosol, NO2, and HCHO vertical profiles from multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations for the first time over Thessaloniki, Greece. We use two independent inversion algorithms for the profile retrievals. We evaluate their performance, we intercompare their results, and we validate their products with ancillary data, measured by other co-located reference instruments.
Ilias Fountoulakis, Henri Diémoz, Anna Maria Siani, Alcide di Sarra, Daniela Meloni, and Damiano M. Sferlazzo
Atmos. Chem. Phys., 21, 18689–18705, https://doi.org/10.5194/acp-21-18689-2021, https://doi.org/10.5194/acp-21-18689-2021, 2021
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The variability and trends of solar spectral UV irradiance have been studied for the periods 1996–2020 (for Rome) and 2006–2020 (for Lampedusa, Rome, and Aosta) with respect to the variability and trends of total ozone and geopotential height. Analyses revealed increasing UV in particular months at all sites, possibly due to decreasing lower-stratospheric ozone (at Rome in 1996–2020) and decreasing attenuation by aerosols and/or clouds (at all stations in 2006–2020).
Stavros-Andreas Logothetis, Vasileios Salamalikis, Antonis Gkikas, Stelios Kazadzis, Vassilis Amiridis, and Andreas Kazantzidis
Atmos. Chem. Phys., 21, 16499–16529, https://doi.org/10.5194/acp-21-16499-2021, https://doi.org/10.5194/acp-21-16499-2021, 2021
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This study investigates the temporal trends of dust optical depth (DOD; 550 nm) on global, regional and seasonal scales over a 15-year period (2003–2017) using the MIDAS (ModIs Dust AeroSol) dataset. The findings of this study revealed that the DOD was increased across the central Sahara and the Arabian Peninsula, with opposite trends over the eastern and western Sahara, the Thar and Gobi deserts, in the Bodélé Depression, and in the southern Mediterranean.
Xinyuan Hou, Martin Wild, Doris Folini, Stelios Kazadzis, and Jan Wohland
Earth Syst. Dynam., 12, 1099–1113, https://doi.org/10.5194/esd-12-1099-2021, https://doi.org/10.5194/esd-12-1099-2021, 2021
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Solar photovoltaics (PV) matters for the carbon neutrality goal. We use climate scenarios to quantify climate risk for PV in Europe and find higher PV potential. The seasonal cycle of PV generation changes in most places. We find an increase in the spatial correlations of daily PV production, implying that PV power balancing through redistribution will be more difficult in the future. Thus, changes in the spatiotemporal structure of PV generation should be included in power system design.
Panagiotis G. Kosmopoulos, Stelios Kazadzis, Alois W. Schmalwieser, Panagiotis I. Raptis, Kyriakoula Papachristopoulou, Ilias Fountoulakis, Akriti Masoom, Alkiviadis F. Bais, Julia Bilbao, Mario Blumthaler, Axel Kreuter, Anna Maria Siani, Kostas Eleftheratos, Chrysanthi Topaloglou, Julian Gröbner, Bjørn Johnsen, Tove M. Svendby, Jose Manuel Vilaplana, Lionel Doppler, Ann R. Webb, Marina Khazova, Hugo De Backer, Anu Heikkilä, Kaisa Lakkala, Janusz Jaroslawski, Charikleia Meleti, Henri Diémoz, Gregor Hülsen, Barbara Klotz, John Rimmer, and Charalampos Kontoes
Atmos. Meas. Tech., 14, 5657–5699, https://doi.org/10.5194/amt-14-5657-2021, https://doi.org/10.5194/amt-14-5657-2021, 2021
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Large-scale retrievals of the ultraviolet index (UVI) in real time by exploiting the modern Earth observation data and techniques are capable of forming operational early warning systems that raise awareness among citizens of the health implications of high UVI doses. In this direction a novel UVI operating system, the so-called UVIOS, was introduced for massive outputs, while its performance was tested against ground-based measurements revealing a dependence on the input quality and resolution.
Antti Arola, William Wandji Nyamsi, Antti Lipponen, Stelios Kazadzis, Nickolay A. Krotkov, and Johanna Tamminen
Atmos. Meas. Tech., 14, 4947–4957, https://doi.org/10.5194/amt-14-4947-2021, https://doi.org/10.5194/amt-14-4947-2021, 2021
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Methods to estimate surface UV radiation from satellite measurements offer the only means to obtain global coverage, and the development of satellite-based UV algorithms has been ongoing since the early 1990s. One of the main challenges in this development has been how to account for the overall effect of absorption by atmospheric aerosols. One such method was suggested roughly a decade ago, and in this study we propose further improvements for this kind of approach.
Myrto Gratsea, Tim Bösch, Panagiotis Kokkalis, Andreas Richter, Mihalis Vrekoussis, Stelios Kazadzis, Alexandra Tsekeri, Alexandros Papayannis, Maria Mylonaki, Vassilis Amiridis, Nikos Mihalopoulos, and Evangelos Gerasopoulos
Atmos. Meas. Tech., 14, 749–767, https://doi.org/10.5194/amt-14-749-2021, https://doi.org/10.5194/amt-14-749-2021, 2021
Antonis Gkikas, Emmanouil Proestakis, Vassilis Amiridis, Stelios Kazadzis, Enza Di Tomaso, Alexandra Tsekeri, Eleni Marinou, Nikos Hatzianastassiou, and Carlos Pérez García-Pando
Atmos. Meas. Tech., 14, 309–334, https://doi.org/10.5194/amt-14-309-2021, https://doi.org/10.5194/amt-14-309-2021, 2021
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We present the development of the MIDAS (ModIs Dust AeroSol) data set, providing daily dust optical depth (DOD; 550 nm) at a global scale and fine spatial resolution (0.1° x 0.1°) over a 15-year period (2003–2017). It has been developed via the synergy of MODIS-Aqua and MERRA-2 data, while CALIOP and AERONET retrievals are used for its assessment. MIDAS upgrades existing dust observational capabilities, and it is suitable for dust climatological studies, model evaluation, and data assimilation.
Kaisa Lakkala, Jukka Kujanpää, Colette Brogniez, Nicolas Henriot, Antti Arola, Margit Aun, Frédérique Auriol, Alkiviadis F. Bais, Germar Bernhard, Veerle De Bock, Maxime Catalfamo, Christine Deroo, Henri Diémoz, Luca Egli, Jean-Baptiste Forestier, Ilias Fountoulakis, Katerina Garane, Rosa Delia Garcia, Julian Gröbner, Seppo Hassinen, Anu Heikkilä, Stuart Henderson, Gregor Hülsen, Bjørn Johnsen, Niilo Kalakoski, Angelos Karanikolas, Tomi Karppinen, Kevin Lamy, Sergio F. León-Luis, Anders V. Lindfors, Jean-Marc Metzger, Fanny Minvielle, Harel B. Muskatel, Thierry Portafaix, Alberto Redondas, Ricardo Sanchez, Anna Maria Siani, Tove Svendby, and Johanna Tamminen
Atmos. Meas. Tech., 13, 6999–7024, https://doi.org/10.5194/amt-13-6999-2020, https://doi.org/10.5194/amt-13-6999-2020, 2020
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The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (S5P) satellite was launched on 13 October 2017 to provide the atmospheric composition for atmosphere and climate research. Ground-based data from 25 sites located in Arctic, subarctic, temperate, equatorial and Antarctic
areas were used for the validation of the TROPOMI surface ultraviolet (UV) radiation product. For most sites 60 %–80 % of TROPOMI data was within ± 20 % of ground-based data.
Anna Gialitaki, Alexandra Tsekeri, Vassilis Amiridis, Romain Ceolato, Lucas Paulien, Anna Kampouri, Antonis Gkikas, Stavros Solomos, Eleni Marinou, Moritz Haarig, Holger Baars, Albert Ansmann, Tatyana Lapyonok, Anton Lopatin, Oleg Dubovik, Silke Groß, Martin Wirth, Maria Tsichla, Ioanna Tsikoudi, and Dimitris Balis
Atmos. Chem. Phys., 20, 14005–14021, https://doi.org/10.5194/acp-20-14005-2020, https://doi.org/10.5194/acp-20-14005-2020, 2020
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Stratospheric smoke particles are found to significantly depolarize incident light, while this effect is also accompanied by a strong spectral dependence. We utilize scattering simulations to show that this behaviour can be attributed to the near-spherical shape of the particles. We also examine whether an extension of the current AERONET scattering model to include the near-spherical shapes could be of benefit to the AERONET retrieval for stratospheric smoke associated with enhanced PLDR.
Ilias Fountoulakis, Henri Diémoz, Anna Maria Siani, Gregor Hülsen, and Julian Gröbner
Earth Syst. Sci. Data, 12, 2787–2810, https://doi.org/10.5194/essd-12-2787-2020, https://doi.org/10.5194/essd-12-2787-2020, 2020
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In this study we discuss the procedures and the technical aspects which ensure the high quality of the measurements of the global solar ultraviolet (UV) irradiance performed by a Bentham spectroradiometer located at Aosta–Saint-Christophe (north-western Alps), Italy. This particular instrument is the reference for the Aosta Valley UV monitoring network, which is the first UV monitoring network in Italy. The final spectra constitute one of the most accurate datasets globally.
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Short summary
Megacities' air quality is determined by atmospheric aerosols. We focus on changes over the last two decades in the 81 largest cities, using satellite data. European and American cities have lower aerosol compared to African and Asian cities. For European, North American and East Asian cities, aerosols are decreasing over time, especially in China and the US. In the remaining cities, aerosol loads are increasing, particularly in India.
Megacities' air quality is determined by atmospheric aerosols. We focus on changes over the last...
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